In order to further enhance oil recovery of the reservoirs, after polymer flooding, two strains of bacterium that could be used on microbial profile modification have been screened. The bacteria are separated from the fluid sample produced within the commercial polymer flooding blocks of Daqing oil-field, and named DT-1 and DT-2. The evaluation of performance shows that these two microorganisms could not only adapt to the special conditions of the reservoirs after polymer flooding, but also could grow well with the in-situ microorganisms. The results of physical simulation core flooding proved that injection profile modification bacteria play a good part in plugging after polymer flooding (the rate of plugging is more than 70%) and oil recovery could be improved about 3.9%(OOIP). In order to demonstrate the technique might as well be feasible, for the first time, after Daqing oilfield polymer is flooding, the test area carries through microbe injection pilot tracey in the world wide. The test data of two adjustment wells interpret that the permeability rate of north2 -fourth 5-p16 well falls to 45.18%, the second half year's adjustment of permeability rate is measured 393.7×10−3μm2, that is compared with the former adjustment still falling to 34.54%. At the same time, injection pressure of 2-fourth 5-p16 well by injection profile modification preceding 8.0mpa comes up to 9.4MPa, rising clearly 1.4MPa; the injection pressure of north 2-4 -p26 well rises 0.8MPa. The six environmental production wells are compared with the former adjustment, containing water decreases 3.9%, the daily production oil ekes 16t, the accumulative amount of oil totally increases 1300t. After microbial treatment, injection profile has been changed greatly, which some of the old taking-fluid zones disappear or others taking more of the fluid become taking less of that and several new zones are taking water. As a result, water cut has decreased and oil production has increased. This study has provided a good method for enhancing oil recovery after polymer flooding.

You can access this article if you purchase or spend a download.